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刘松涛 《农业装备与车辆工程》2009,(8):40-42
从分析衬板的断裂机理入手,通过试验,对比验证了特定材料在一定条件下,由于热处理工艺不同,材料失效将由韧性断裂向准解理、解理等脆性断裂过渡,强度和硬度也随着下降,同时重现了材料断裂的内在起因--舌状花样或微裂纹,并结合试验现象讨论了材料热处理的本质. 相似文献
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The number of circulating erythrocytes was monitored in two strains of brown trout during the spawning season. Erythrocyte numbers were significantly elevated in mature male fish of both strains compared with mature females or immature fish. This period of erythrocytosis coincided with elevated plasma 11-ketotestosterone levels in mature male fish, was out of phase with the testosterone peak in males and was not observed in females despite high levels of plasma testosterone. The results are discussed with reference to the control of erythropoiesis in higher vertebrates. 相似文献
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Burkhard MJ Brown DE McGrath JP Meador VP Mayle DA Keaton MJ Hoffman WP Zimmermann JL Abbott DL Sun SC 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2001,30(2):76-85
Anemia was induced in weanling Sprague Dawley rats either by feeding an iron-deficient diet or by chronic phlebotomy. The erythroid regenerative response was then evaluated before and after a hemolytic event, and results were compared with those of a third group of control nonphlebotomized rats fed an iron-replete diet. Diet and phlebotomy groups developed a similar degree of anemia (mean hemoglobin concentration 7.9 g/dL and 7.8 g/dL, respectively; controls, 13.9 g/dL) and hypoferremia (mean serum iron concentration 25.4 microgram/dL and 34.9 microgram/dL, respectively; controls, 222.0 microgram/dL). However, the anemia in diet rats was nonregenerative (reticulocyte count, 83.1 X 10(3) cells/microliter) and associated with bone marrow erythroid hypoplasia; whereas the anemia in phlebotomy rats was regenerative (reticulocyte count, 169.6 X 10(3) cells/microliter) and associated with bone marrow erythroid hyperplasia. Thrombocytosis was seen in diet rats (1,580 X 10(3) cells/microliter) but not phlebotomy rats (901 X 10(3) cells/microliter) when compared with controls (809 X 10(3) cells/microliter). To further evaluate the regenerative capability, phenylhydrazine (PHZ) was administered to induce hemolysis. Erythrocyte mass declined approximately 25% in all groups, including controls. The reticulocytosis (265.3 X 10(3) cells/microliter) seen in phlebotomy rats was earlier and significantly greater than that seen in either diet or control rats. Hemoglobin concentration returned to pre-PHZ concentrations (7.9 g/dL) in phlebotomy rats within 4 days posthemolysis. In diet rats, the maximal regenerative response (176.3 X 10(3) cells/microliter) was not seen until 8 days posthemolysis, and hemoglobin (7.5 g/dL) did not return to pre-PHZ concentrations during the 8-day study. In many aspects, the anemia seen following diet- or phlebotomy-induced iron deficiency was similar. However, the erythroid regenerative capability varied depending on the mechanism by which anemia was induced and furthermore altered the efficiency of hemoglobin production following a hemolytic event. These results suggest that the availability of iron in the diet may modulate the pathogenesis of iron deficiency anemia. 相似文献
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Analysis and Applicati on High- Efficacy Saving Energy Technique of Central Air - Conditioning System 
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下载免费PDF全文 Aimins at the state that present central air- conditioning systems performance in high ineffective energy consumption, this paper studies the reasons of ineffective energy consumption and the key technique to solove the problem. A set of energe saving device for central air - conditioning systems is developed. A system dynamical mathematical model is established in theory, and an optimal performance pattern is fired. The central air - conditioning system can work in the optimal pattern with effective comfortability and saving energy by using. The device may save power rate to 22.6% by survey and may have broad market prospect in the southern area. 相似文献
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Pronephric and splenic involvements in erythropoiesis and in stress-induced hematological response by goldfish,Carassius auratus, were examined under conditions of minimal stress and following transient (3h) temperature-induced elevation of O2 demand and transient (3h) exposure to hypoxia. Although hemoglobin content and red cell numbers were little affected, the ontogenic composition of the circulating erythrocyte population was significantly altered by both types of respiratory challenge and also by the stresses associated with capture, air exposure during transfer and intraperitoneal administration of label. Juvenile cell numbers increased sharply while mature erythrocyte abundances declined. Consistent with this, [3H] methylthymidine-labeled cell numbers rose in both spleen and pronephros following imposition of stress. Splenic erythropoietic activity was modest relative to that of the pronephros. Our observations point to a readily triggered response involving: [1] release of cells reservoired in the spleen and pronephros, [2] increased erythropoiesis and [3] karyorrhexis. We suggest that while the magnitude of response may depend on the quality and magnitude of the imposed stress, its central features are essentially constant. 相似文献
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分别以培杂泰丰和粤晶丝苗为材料,采用水培方法,通过设计不同的栽插孔穴直径(栽插孔径分别为20、28、35 mm,依次记为D1、D2、D3)限制水稻的无效分蘖,研究抑制无效分蘖对不同基因型水稻的产量和非结构性碳水化合物的影响。结果表明:与D1、D3相比,D2显著提高了水稻培杂泰丰和粤晶丝苗的成穗率和每穗总粒数,最终显著增加了水稻产量;D2、D3处理水稻茎鞘非结构性碳水化合物含量显著高于D1处理,D3处理水稻培杂泰丰和粤晶丝苗抽穗后叶面积大,茎鞘非结构性碳含量高,但主要供给营养器官,对产量贡献少;水稻培杂泰丰和粤晶丝苗幼穗分化期的茎鞘非结构性碳水化合物含量与每穗总粒数呈显著正相关关系。 相似文献